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27
Bacteriological Analysis.
On gelatine plates, kept for four days at 20° C., 21 colonies per
1 cc. developed, none of these liquified gelatine.
On Agar plates, kept for 24 hours at 37° C. 6 colonies per 1 cc.
developed.
B. Coli (types) absent in 1 cc.s.
Streptococci absent in 5 cc.
B. Enteritidis sporogenes absent in 5 cc.
DRAINAGE AND SEWERAGE.
Extension to Sewage Disposal Works.— On December 9, 1933,
the extension to the Wandle Valley Sewerage Board Disposal
Works was opened by the Chairman of the Board. The cost of the
extensions, which have been completed, is about £115,000. The
works included in the extension comprise the provision of screening
plant, sewage and sludge pumping station, sedimentation tanks,
bacteria beds and humus tanks, as well as storm water tanks and
extensions of the arrangements and plant for sludge pressing. The
whole of the pumping plant is electrically driven and automatically
controlled by means of float switches, in order to ensure that the
number of pumps in operation at any time will be in relation to the
flow of sewage without the necessity of constant supervision by an
attendant.
The sludge from all the tanks in the new extension gravitates
to a sludge well situated at the new pumping station, and is then
pumped back to the sludge press house, where the moisture content
is reduced by pressing, to enable it to be readily handled for transport.
The press house has been extended and four new presses,
each 30 cwt. capacity, have been installed to deal with the
additional quantity of sludge collected in the new settling tanks.
The whole of the sewage is brought to the works by high-level and
low-level systems of sewers. The high-level sewage is passed
through screens with mechanical raking gear, but as the low-level
sewage is pumped by special Stereophagus pumps, which break up all
large solids, it is unnecessary to install screens for this portion of
the sewage flow.